scholarly journals Post-Tensioning Steel Rod System for Flexural Strengthening in Damaged Reinforced Concrete (RC) Beams

2018 ◽  
Vol 8 (10) ◽  
pp. 1763
Author(s):  
Swoo-Heon Lee ◽  
Kyung-Jae Shin ◽  
Hee-Du Lee
Keyword(s):  
Reinforced Concrete ◽  
Load Resistance ◽  
Reinforced Concrete Beams ◽  
Design Parameters ◽  
Flexural Strengthening ◽  
Three Point Bending ◽  
Rod System ◽  
Load Carrying ◽  
Post Tensioning ◽  
Post Tensioned

In this study, a post-tensioning method using externally unbonded steel rods was applied to pre-damaged reinforced concrete beams for flexural strengthening. Nine simply-supported beams, three reference beams and six post-tensioned beams, were subjected to three-point bending. The design parameters observed in this study were the amount of tension reinforcements (3-D19, 4-D19, and 2-D22 + 2-D25; “D” indicates the nominal diameter of the rebar) and the diameters of the external rod (φ22 mm and φ28 mm). A V-shaped profile with a deviator at the bottom of the mid-span was applied to the pre-damaged beams, and a post-tensioning force was added to overcome the low load resistance and deflection already incurred in the pre-loading state. The post-tensioning force caused by tightening the nuts at the anchorage corresponded to a strain of 2000 με in the external rods; this value was approximately equal to the strain caused by torque that two adults can apply conveniently. The post-tensioning system increased the load-carrying capacity and flexural stiffness by approximately 40–112% and 28–73%, respectively, when compared with the control beams. However, the external rods did not yield in the post-tensioned beam with larger steel reinforcements and external steel rods. The external rod with the larger diameter increased the flexural strength more effectively.

scholarly journals Flexural strengthening of beams using post-tensioned metal straps fully wrapped around steel channels anchored to normal steel reinforced concrete beams

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253816
Author(s):  
Wrya Abdullah ◽  
Serwan Khwrshid Rafiq
Keyword(s):  
Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Load Carrying Capacity ◽  
Factors Affecting ◽  
Flexural Strengthening ◽  
Steel Reinforced Concrete ◽  
Load Carrying ◽  
Main Variable ◽  
Novel Method ◽  
Post Tensioned

The efficacy of post-tensioned metal straps PTMS, wrapped around steel channels anchored to normal reinforced concrete (R.C) beams is tested in increasing the flexural capacity of the beams. For this purpose, nine normal R.C beams with dimensions of 160 mm x 240 mm x 2100 mm are constructed to fail in bending. The location and the number of the straps are considered as the main variable. It is found that using PTMS can enhance the load-carrying capacity of the beam by 29% to 63%. The decisive factors affecting the increase are the location of the straps (at the bottom or sides), shape of the flange and web edges (squared or rounded) and alignment of the flanges (vertical or inclined). A complete guide can be found in the paper as it is a novel method of strengthening beams which can be applied to the beams cast in place with integral slabs.

scholarly journals BEHAVIOUR OF REINFORCED CONCRETE BEAMS WITHOUT STIRRUPS SUBJECTED TO STEEL REINFORCEMENT CORROSION

2016 ◽  
Vol 22 (2) ◽  
pp. 146-153 ◽  
Author(s):  
Rizwan AZAM ◽  
Ahmed K. EL-SAYED ◽  
Khaled SOUDKI
Keyword(s):  
Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Load Carrying Capacity ◽  
Longitudinal Reinforcement ◽  
Rc Beams ◽  
Test Results ◽  
Structural Behaviour ◽  
Three Point Bending ◽  
Load Carrying ◽  
Crack Widths

The effect of corrosion on the structural behaviour of reinforced concrete (RC) beams without stirrups was experimentally investigated. A total of seven medium-scale RC beams without stirrups were constructed. The beams measured 150 mm wide, 250 mm deep and 1700 mm long. The test variables included: three different longitudinal reinforcement ratios (0.91%, 1.21%, and 1.82%) and two different corrosion levels (3% and 10%). Four beams were subjected to artificial corrosion whereas three beams acted as control un-corroded. Following the corrosion phase, all beams were tested to failure in three point bending. Corrosion crack widths and cracking patterns were recorded at different stages of corrosion. The effect of different longitudinal reinforcement ratios on the rate of corrosion was observed. Test results revealed that the beams with higher reinforcement ratios experienced slower corrosion rate compared to beams with lower reinforcement ratios. All control beams failed in shear whereas corroded beams failed in bond. There was a significant reduction in the load carrying capacity of the corroded beams without stirrups compared to the control beams.

scholarly journals Experimental assessment of the performance of reinforced concrete beams strengthened with carbon fiber reinforced polymer laminates

2020 ◽  
Vol 39 (1) ◽  
pp. 105-112
Author(s):  
N. Yusuf ◽  
J.M. Kaura ◽  
A. Ocholi ◽  
M. Abbas
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Rc Beams ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Flexural Performance ◽  
Load Carrying ◽  
Ultimate Load Carrying Capacity

In this study, experimental research is carried out to assess the flexural performance of RC beams strengthened with different amount of CFRP laminates at the tension face. Twelve rectangular RC beams were fabricated and three are un-strengthened and used as reference beams and the remaining nine are strengthened with different amount of CFRP varying from single to triple layers and all are tested to failure under three points bending test. The increase of ultimate strength provided by the bonded CFRP laminates is assessed and failure modes is identified and compared to the un-strengthened RC beams. The results indicated that the flexural capacity of the beams was significantly improved as the amount of the laminates increases that ranged from 20% to 52% increased for single to triple layers laminates. It is concluded that the attachment of CFRP laminates has substantial influence on the performance of CFRP strengthened RC beams. Based on the observed results, recommendations are made that externally application of CFRP laminates can be used for a significant enhancement of the strength deficient RC beams in increasing the ultimate load carrying capacity. Keywords: CPRP laminate, Reinforced concrete, ductility, index, epoxy resin, flexural strengthening

scholarly journals Strengthening of Reinforced Concrete Members using Post-Tension Cables: A Parametric Research

2019 ◽  
Vol 8 (2S3) ◽  
pp. 1334-1338
Keyword(s):  
Reinforced Concrete ◽  
Parametric Study ◽  
Concrete Beams ◽  
Load Capacity ◽  
Reinforced Concrete Beams ◽  
Design Parameters ◽  
Internal Stresses ◽  
Force Magnitude ◽  
Post Tensioning ◽  
Post Tension

In building construction, post-tensioning allows longer clear spans, thinner slabs than the reinforced concrete beams. This paper presents a theoretical investigation on the behavior of existing reinforced concrete beams strengthened with post-tensioning cable(s) for increasing their load capacity. The proposed post-tensioning technique consists of stressing cable passing through a structural beam element starting from the top/bottom side and traversing the beam to the bottom/top side and then return back to the original side. A theoretical parametric study is conducted to study the effect of post-tensioning parameters on the internal stresses to optimize the design parameters. An excel spread sheet program was developed to calculate the internal straining actions at critical sections of the beam. A parametric study including the cable length, inclination angle of the cable and pre-stressing force magnitude was performed by using this program. This parametric study, led to well-defined guidelines for the proper use of the strengthening of beams by pre-stressing cables with adequate geometrical conditions of the cables

Parametric study of truss bridges by the post-tensioning method

2005 ◽  
Vol 32 (2) ◽  
pp. 420-429 ◽  
Author(s):  
Kyoung-Bong Han ◽  
Sun-Kyu Park
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
High Strength ◽  
Elastic Behavior ◽  
Design Parameters ◽  
Load Carrying Capacity ◽  
Prestressing Force ◽  
Load Carrying ◽  
Post Tensioning ◽  
Post Tensioned

The post-tensioning method has been successfully used to improve the performance of existing concrete structures. Applications of the method are rare in steel structures, however. Post-tensioning using high-strength cables or bars can be effectively used to increase the working load carrying capacity of steel structures. In this paper, the elastic behavior of post-tensioned trusses with straight and draped tendon profiles for truss strengthening is examined. The effects of design parameters such as the tendon profile, truss type, prestressing force, and tendon eccentricity on working load and deflection of trusses are studied. The results show that the allowable load of a truss increases proportionally with the increase in prestressing force and eccentricity. Post-tensioning enlarges the elastic range, increases the redundancy, and reduces the deflection and member stresses, eventually increasing the load-carrying capacity of truss bridges.Key words: post-tensioning method, steel structures, post-tensioned trusses, truss strengthening, design parameters, load-carrying capacity.

scholarly journals RESEARCH OF THE WORK OF REINFORCED CONCRETE BENDED ELEMENTS WITH THE USE OF POST-TENSIONED ROPES

2020 ◽  
Vol 10 (1) ◽  
pp. 24-29
Author(s):  
Alexander A. PISHCHULEV ◽  
Denis A. PANFILOV ◽  
Yury V. ZHILTSOV ◽  
Yana A. BUZOVSKAYA
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Crack Opening ◽  
Full Scale ◽  
Reinforced Concrete Beams ◽  
Load Carrying Capacity ◽  
Load Bearing Capacity ◽  
Distributed Development ◽  
Load Carrying ◽  
Post Tensioned

The study of full-scale samples of bent reinforced concrete beams using tensioned ropes in a synthetic shell filled with grease is considered in the article. The purpose of the research is to test reinforced concrete beams using post-tensioned ropes to assess the load-bearing capacity and stiffness. Experimental results of studies on bent samples with rope tension and without ropes are presented. The study on full-scale samples revealed a number of features of the work of bent beams with post-tensioned ropes. The use of a post-tensioned rope without coupling with concrete allows for a more evenly distributed development of normal cracks and reduces the width of the crack opening. Pre-tension cable reinforcement increases the load carrying capacity of the area of the transverse bend.

Flexural Performance of Reinforced Concrete Built-up Beams with SIFCON

2020 ◽  
Vol 38 (5A) ◽  
pp. 669-680
Author(s):  
Ghazwan K. Mohammed ◽  
Kaiss F. Sarsam ◽  
Ikbal N. Gorgis
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Concrete Beams ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Load Carrying Capacity ◽  
Conventional Concrete ◽  
Flexural Performance ◽  
Load Carrying ◽  
Fiber Concrete

The study deals with the effect of using Slurry infiltrated fiber concrete (SIFCON) with the reinforced concrete beams to explore its enhancement to the flexural capacity. The experimental work consists of the casting of six beams, two beams were fully cast by conventional concrete (CC) and SIFCON, as references. While the remaining was made by contributing a layer of SIFCON diverse in-depth and position, towards complete the overall depths of the built-up beam with conventional concrete CC. Also, an investigation was done through the control specimens testing about the mechanical properties of SIFCON. The results showed a stiffer behavior with a significant increase in load-carrying capacity when SIFCON used in tension zones. Otherwise high ductility and energy dissipation appeared when SIFCON placed in compression zones with a slight increment in ultimate load. The high volumetric ratio of steel fibers enabled SIFCON to magnificent tensile properties.

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